Utility vehicles (also referred to below as “vehicle” for the sake of greater ease of reading) which are located or moving on inclined surfaces are subjected to an increased risk of tipping over, in particular if they have a high center of gravity. The risk of tipping over is increased for a vehicle that has a pivoting element such as, for example, a dump trough or a crane, mounted thereon. If the pivoting movement of the element is carried out while the vehicle is located on an inclined underlying surface and as a result the vehicle body is inclined laterally, and if the pivoting element moves in the direction of the inclination of the vehicle, this also leads to a displacement of the center of gravity in the same direction.
If the element is pivoted to such an extent that the vector of the weight combined at the center of gravity no longer passes through the supporting surface of the vehicle, the resulting moment causes the vehicle to tip over.
Ride-level-control devices are used to prevent the risk of tipping over. They permit the distance between the wheels and the vehicle body to be changed individually for each wheel, for pairs of wheels or for pairs of axles. This is usually done by means of an electronic control unit that is operated manually by means of an operator control unit, on the basis of visual estimation of the inclination by the driver of the vehicle. Devices of this type for chasses with air suspension are known by the abbreviation “ECAS” and are commercially available. Furthermore, there are also designs with mechanical valves, referred to as rotary slide valves.
Automatic compensating devices that sense the changes in length of the spring elements on one side of the vehicle by means of travel sensors and initiate the compensating movement in accordance with a programmed algorithm are also known (see DE 100 22 834 A1).
The foregoing devices have the common disadvantage that the actual inclination is not sensed directly. The inclined side of the utility vehicle may sink, for example, into soft ground, which is generally encountered in off-road situations, on unmetalled roadways or on construction sites. This is reliably noted neither by the previously known devices nor by the driver of the vehicle.